1. Field of the Invention
The present invention relates to a bottle cap composed of a cap body and an inner plug fitted therein.
2. Description of the Prior Art
There are already known bottle caps of this sort as shown in FIGS. 1 and 2.
The cap shown in FIG. 1 is composed of a cap body 21 and an inner plug 22, and said cap body 21 is provided with a cylindrical body portion 24 having an internal thread 27, an annular radial flange 25 inwardly extending above said thread 27 and a top plate 23. The inner plug 22 is provided, at the uppermost part of a pot-shaped body 28, with an outwardly extending annular radial flange 26 fitted in an annular groove defined between said top plate 23 and the flange 25, and is further provided with a similar flange 29 below said flange 25 to sandwich said flange 25 between the flanges 26 and 29.
The cap shown in FIG. 2 is also composed of a cap body 31 and an inner plug 32, wherein said cap body 31 is provided with a cylindrical body 34 having an internal thread 37 and a top plate 33 integrally formed with said body, while the inner plug 32 is provided, at the center of the bottom of a pot-shaped body 38, with a vertical support member 39 which is fixed to the top plate 33 for attaching said inner plug 32 to the cap body 31.
The filling machine used for fitting the cap of the above-mentioned sort on a bottle is generally designed to fit the inner plug first and then to fit the cap body, after the bottle is filled with a desired content.
However, the cap shown in FIG. 1 or 2 requires a modification in the filling machine since the inner plug is in advance fitted in the cap body.
Also the cap shown in FIG. 1 is inevitably expensive as it is composed of three parts; the inner plug 22, top plate 23 and cap body 24.
On the other hand the cap shown in FIG. 2, in which the inner plug 32 is rigidly attached to the cap body 31, cannot be fitted in the bottle mouth if the inner plug is not sufficiently centered with the bottle mouth.